I had a trip to Durham from Northallerton last Saturday. Very busy with the Miners Gala on.
Outward - 5-car Azuma instead of 9, no reservations, guard said to sit in any available seat.
Return - 9-car Azuma instead of a 225, no reservations, again we were told to find any available seat.
Conversely, on Cross Country York to Birmingham earlier in the week, the first class host accosted me on entry to first class, checked I had a ticket for first class and told me there were no reservations but to make sure to sit in my reserved seat. I had to ask someone to move in order to do so, who was obviously peeved at moving.